UK patent application publication GB 2,298,148-A discloses a coffee mill including a coffee mill hopper. The hopper has two coffee bean compartments and a central outlet in its bottom, which outlet is common to both compartments. The outlet is covered by an apertured cap inside of which a rotatable inverted cup-shaped closure fits that extends to a control knob at the top of the hopper. The cup-shaped closure has an aperture in its side, which cooperates with the apertured cap, so that the rotational position of the cup-shaped closure controls whether coffee beans flow out of the hopper through the common outlet from a first, a second, or both of the compartments.
DE 594983 discloses a coffee mill hopper assembly according to the preamble of claim 1.